<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        div{
            border-width:1px;
            /*border-style:solid;*/   /*实线*/
           /* border-style:dashed;*/    /*虚线*/
            border-style:dotted;     /*点线*/
            border-color:red;
            width:200px;
            height:200px;
        }
    </style>
</head>
<body>
    <div>

    </div>
</body>
</html>